Friction test device and method for simulating sliding and rolling motion form of transmission mechanism

Abstract

The invention discloses a friction test device and method for simulating a sliding and rolling motion form of a transmission mechanism. The test device comprises a three-dimensional mechanical sensor, a torque sensor, a fastening screw group, an upper friction pair sleeve, an upper friction pair clamp, an upper friction pair plate, a raceway disc, a ball, a raceway disc support and a rotary circular truncated cone module. Based on the device and the method provided by the invention, the relative sliding-rolling motion between the ball and the raceway in the transmission mechanism can be simulated, and the real-time monitoring of the sliding-rolling friction coefficient is realized. A friction pair and a special clamp are designed by combining the principle of a friction-wear testing machine, the contact and motion forms of the balls and the raceway are restored, and the friction coefficient is monitored and calculated in real time. The method is of great significance for solving the problem of monitoring the sliding and rolling friction state of a ball-raceway friction contact area caused by the complex internal structure of transmission parts such as a ball screw and the like.

Description

Technical Field

[0001] The present invention relates to a friction test device and method for simulating the rolling and sliding motion form of a transmission mechanism, and relates to the technical field of friction coefficient measurement. Background Art

[0002] Mechanical components such as ball screws and rolling bearings that transmit loads and motions through the rolling and sliding motion between rolling elements and raceways are widely used in industrial manufacturing. During the operation of such components, due to their complex and enclosed internal structures, it is difficult to directly monitor the friction coefficient between their rolling elements and raceways. Most of them can only evaluate the lubrication friction state through indirect means such as monitoring the frictional torque, and it is difficult to accurately obtain the friction coefficient of the rolling element-raceway contact area, which is not conducive to studying the friction and lubrication degradation law under the rolling and sliding motion form of the rolling element-raceway. Summary of the Invention

[0003] The present invention is a friction test device and method that can simulate the rolling and sliding motion form of a transmission mechanism. The rotating turntable drives the raceway disc and the rolling elements to rotate, lubricating grease is added to simulate the actual lubrication situation of mechanical components, and a three-dimensional force sensor is used to collect vector data to calculate the friction coefficient of the contact area.

[0004] The present invention aims to solve the problem that it is difficult to monitor in real time the friction characteristics of the rolling element-raceway in the actual working conditions of the transmission mechanism. By designing a special friction pair and a fixture support, experiments are carried out using a friction and wear testing machine to obtain the friction coefficient between the rolling element and the raceway in the rolling and sliding motion form, and then the lubrication state and wear form are analyzed. The present invention takes the spherical rolling elements in ball screws and rolling bearings as an example, but the shape of the rolling elements is not limited thereto.

[0005] To achieve the above object, the following technical solutions are adopted: In the first aspect: A friction test device for simulating the rolling and sliding motion form of a transmission mechanism of the present invention generally consists of a three-dimensional mechanical sensor, a set of fastening screws (M4, M3X10, M2X6), a torque sensor, an upper friction pair sleeve, an upper friction pair fixture, an upper friction pair plate, a raceway disc, a ball, a raceway disc support, and a rotating turntable module. The three-dimensional mechanical sensor, the torque sensor, and the rotating turntable module are installed at the corresponding positions of the friction and wear testing machine. The rotating turntable module is connected to the drive power supply line and the program control board card, and the three-dimensional mechanical sensor and the torque sensor are connected to the drive power supply line and the data acquisition board card. The raceway disc support is bolted to the rotating turntable module using 6 M2 screws to ensure that the pre-tightening forces of each screw are basically the same. A torque wrench is used to tighten the screws and a level is used for leveling. The raceway disc is bolted to the corresponding position of the raceway disc support using four M3 screws, and an appropriate amount of lubricating grease and balls are added to the raceway. Each of the front and back sides of the raceway disc is provided with two raceways with different radii for multiple tests and sampling observation and characterization after the tests. The polished upper friction pair plate and the upper friction pair fixture are bolted together using six M3 screws, and then an M4 screw is used to tighten the upper friction pair sleeve to prevent the upper friction pair fixture from rotating and shifting during the rolling and sliding test. The assembled upper friction pair sleeve is installed at the corresponding position at the bottom of the torque sensor, and then the torque sensor is installed at the corresponding position of the three-dimensional mechanical sensor. The real-time friction coefficient is obtained by setting the load, the rotation speed of the rotating turntable module, and calculating the equivalent radius of the friction coefficient. The calculation process of the equivalent radius is as follows:

[0006]

[0007] By combining Equation (1) and Equation (2), the equivalent radius r for calculating the rolling and sliding friction coefficient input to the upper computer can be obtained 0 .

[0008] T Frictional torque; r 1 Inner diameter of the friction contact area; r 2 Outer diameter of the friction contact area; μ Friction coefficient; r Radius of the differential arc relative to the rotation center; σ Contact stress at the microelement; Fz Longitudinal pressure; r 0 Equivalent radius;

[0009] In the second aspect, the present invention includes a friction test method for simulating the rolling and sliding motion form of a transmission mechanism. Based on the above test device, the test method includes the following steps:

[0010] Step 1: Install the three-dimensional mechanical sensor, the torque sensor, and the rotating turntable module in the test device at the corresponding positions of the friction and wear testing machine, and connect them to the upper computer through the data acquisition card and the program control board card, and turn on the power to achieve start and stop.

[0011] Step 2: Use the host computer to control the central position of the torque sensor, align it with the center of the rotating turntable module, and set it as the coordinate zero point.

[0012] Step 3: Bolt and install the raceway disc on the raceway disc support with M3 screws, and install the raceway disc support on the rotating turntable module with M2 screws to complete the assembly of the bottom friction pair and the drive module.

[0013] Step 4: Bolt and connect the upper friction pair piece to the upper friction pair fixture with M3 screws, install the upper friction pair fixture on the upper friction pair sleeve with M4 screws, and then install the upper friction pair sleeve at the corresponding position at the bottom of the torque sensor to complete the assembly of the upper friction pair and the mechanical signal measurement module.

[0014] Step 5: Apply an appropriate amount of grease to the raceway of the raceway disc and install the ball bearings. Use the host computer to control the positions of the torque sensor and the three-dimensional mechanical sensor so that the upper friction pair piece contacts the ball bearings. Control the rotation of the rotating turntable module to evenly apply the grease in the friction contact area and complete the trial rotation and warm-up.

[0015] Step 6: Set the rotation speed and load of the sliding-rolling friction test through the host computer, calculate and input the equivalent radius r 0 , and the duration of the friction test, and start the sliding-rolling friction test.

[0016] Step 7: Collect and process the collected mechanical signals through the host computer, and output the real-time friction coefficient between the ball bearings and the upper friction pair piece after calculation and processing.

[0017] Step 8: Obtain the friction coefficient between the ball bearings and the raceway of the raceway disc through the calculated equivalent radius between the ball bearings and the raceway of the raceway disc.

[0018] The present invention has the following advantages due to the above technical solutions:

[0019] 1. The overall test device has a simple structure, the involved parts are easy to process, the processing quality and accuracy are guaranteed, it can truly restore the ball-raceway sliding-rolling friction motion form in the transmission mechanism, and the assembly is convenient and reliable, providing convenience for studying the dynamic friction characteristics of sliding-rolling.

[0020] 2. The open design enables the real-time observation of the motion form of the ball bearings in the raceway and the real-time and accurate measurement of the friction coefficient.

[0021] 3. It can accurately control the contact stress and rotation speed of the sliding-rolling friction test and study the sliding-rolling friction and wear laws under different working conditions. Description of the Drawings

[0022] Figure 1 Schematic diagram of the friction contact area for calculating the equivalent radius.

[0023] Figure 2 This is the overall assembly drawing.

[0024] Figure 3 This is the exploded view. Specific implementation manners

[0025] To more clearly illustrate the purpose, technical solution and advantages of the present invention, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0026] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of description, and does not indicate or imply that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation to the present invention. Without otherwise stated, the above-mentioned terms have no special meaning and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "connection" and "bolting connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0028] In the description of the present invention, the ball screw and the rolling bearing are taken as examples for the embodiments. The rolling elements are taken as GCr15 balls, and the materials of the upper friction pair and the raceway disc are taken as 9Cr18, but the present invention is not limited thereto.

[0029] A friction test device for simulating the rolling and sliding motion form of a transmission mechanism according to the present invention generally consists of a three-dimensional mechanical sensor 1, a set of fastening screws (M4, M3X10, M2X6), a torque sensor 2, an upper friction pair sleeve 3, an upper friction pair fixture 5, an upper friction pair piece 6, a raceway disk 9, a ball 8, a raceway disk support 11, and a rotating turntable module 12. Among them, two pairs of raceways with different radii are provided on both sides of the raceway disk 9, and the material is 9Cr18. The matching ball 8 is made of GCr15 material. The upper friction pair fixture 5 and the raceway disk support 11 are made of 316 stainless steel, and the upper friction pair piece 6 is made of the same 9Cr18 material as the raceway disk 9. The test device provided by the present invention can restore the relative rolling and sliding motion state of the ball-raceway in the transmission mechanism and monitor the friction coefficient, providing convenience for the research on the rolling and sliding friction characteristics of the ball-raceway in the transmission mechanism.

[0030] The following takes a friction test device for simulating the rolling and sliding motion form of a ball-raceway in a transmission mechanism as a specific embodiment to elaborate in detail on the specific implementation scheme of the present invention, but the present invention is not limited thereto.

[0031] As Figure 1 and Figure 2 shown, a friction test device for simulating the rolling and sliding motion form of a transmission mechanism provided in this embodiment generally consists of a three-dimensional mechanical sensor 1, a set of fastening screws (M4, M3X10, M2X6), a torque sensor 2, an upper friction pair sleeve 3, an upper friction pair fixture 5, an upper friction pair piece 6, a raceway disk 9, a ball 8, a raceway disk support 11, and a rotating turntable module 12. The assembly and construction steps are as follows:

[0032] Step 1: Install the three-dimensional mechanical sensor 1, the torque sensor 2, and the rotating turntable module 12 at the corresponding positions of the friction and wear testing machine. The rotating turntable module 12 is connected to the drive power supply line and the program control board, and the three-dimensional mechanical sensor 1 and the torque sensor 2 are connected to the drive power supply line and the data acquisition board.

[0033] Step 2: Bolt the raceway disk support 11 to the rotating turntable module 12 using six M2 screws 10, ensuring that the pre-tightening forces of each screw are basically the same. Tighten using a torque wrench and level with a spirit level. Bolt the raceway disk 9 to the corresponding position of the raceway disk support 11 using four M3 screws 7, and add an appropriate amount of lubricating grease and the ball 8 to the raceway.

[0034] Step 3: Bolt and connect the polished upper friction pair piece 6 and the upper friction pair fixture 5 using six M3 screws 7, and then tighten the upper friction pair sleeve 3 using one M4 screw 4 to prevent the upper friction pair fixture 5 from rotating and shifting during the rolling and sliding test. Install the assembled upper friction pair sleeve 3 at the corresponding position at the bottom of the torque sensor 2, and then install the torque sensor 2 at the corresponding position of the three-dimensional mechanical sensor 1.

[0035] Step 4: Calculate the equivalent radius of the friction coefficient input into the host computer. The calculation process is as follows:

[0036]

[0037] Formula (1) is the formula for calculating the overall friction torque in the friction area. According to Hertz contact theory, elastic deformation occurs when the ball contacts the upper friction plate, and the contact area between the two is actually an elliptical area. Therefore, when the ball and the upper friction plate perform relative sliding and rolling motion, the actual friction area is a circular ring. 2 、r 1 are the outer diameter and inner diameter of the actual friction contact area, μ is the friction coefficient, r is the radius of the differential arc relative to the rotation center, σ is the contact stress at the microelement, the friction torque at the microelement is calculated and then integrated over the actual friction contact area to calculate the friction torque. Formula (2) is the formula for calculating the friction coefficient using the friction torque measured by the torque sensor and the vertical pressure measured by the three-dimensional mechanical sensor in the upper computer of the friction and wear testing machine, where Fz is the vertical pressure measured by the three-dimensional mechanical sensor, r 0 This is the equivalent radius set for the input host computer. By combining equations (1) and (2), we can obtain the outer and inner diameters r of the friction contact area. 2 、r 1 Calculate the equivalent radius r 0 The calculation formula (3) is used to calculate the equivalent radius r between the ball and the raceway of the raceway. 0 *, r 0 With r 0 The ratio of * is the inverse ratio of the upper and lower friction coefficients of the ball, and the friction coefficient between the ball and the raceway of the raceway can be obtained.

[0038] Based on the friction test device for simulating the sliding motion of a ball-roller in a transmission mechanism provided in the above embodiment, the present invention further provides a friction test method for simulating the sliding motion of a transmission mechanism, comprising the following steps:

[0039] Step 1: Install the three-dimensional mechanical sensor 1, torque sensor 2, and rotating table module 12 in the test device at the corresponding positions of the friction and wear testing machine, and connect them to the host computer through a data acquisition line.

[0040] Step 2: Use the host computer to control the center position of the torque sensor 2 and align it with the center of the rotating table module 12, setting it as the coordinate zero point.

[0041] Step 3: Bolt the raceway disc 9 onto the raceway disc support 11 through the M3 screws 7, and install the raceway disc support 11 onto the rotating frustum module 12 through the M2 screws 10 to complete the assembly of the bottom friction pair and the drive module.

[0042] Step 4: Bolt the upper friction pair piece 6 to the upper friction pair fixture 5 through M3 screws 7, install the upper friction pair fixture 5 on the upper friction pair sleeve 3 through M4 screws 4, and then install the upper friction pair sleeve 3 at the corresponding position at the bottom of the torque sensor 2 to complete the assembly of the upper friction pair and the mechanical signal measurement module.

[0043] Step 5: Apply an appropriate amount of grease to the raceway of the raceway disk 9, install the ball 8, use the host computer to control the upper friction pair piece 6, the torque sensor 2, and the three-dimensional mechanical sensor 1 to contact the ball 8, control the rotation of the rotating turntable module 12 to rotate, evenly apply the grease in the friction contact area, and complete the trial rotation and warm-up.

[0044] Step 6: Set the rotation speed, load, and equivalent radius r 0 of the sliding-rolling friction test and the duration of the friction test through the host computer, and start the sliding-rolling friction test.

[0045] Step 7: Collect and process the collected mechanical signals through the host computer, and output the real-time friction coefficient between the ball 8 and the upper friction pair piece 6 after calculation and processing.

[0046] Step 8: Obtain the friction coefficient between the ball and the raceway of the raceway disk 9 through the calculated equivalent radius between the ball 8 and the raceway of the raceway disk 9. The embodiments of the present invention at least bring the following beneficial technical effects:

[0047] The embodiments of the present invention provide a convenient technical means for sliding-rolling friction tests to solve the problems of difficult observation of the contact area of the ball-raceway sliding-rolling contact transmission component and the inability to measure the accurate friction coefficient. By restoring the contact motion form of the ball-raceway, using sensors to collect mechanical signals, and calculating the friction coefficient, it is used to evaluate the sliding-rolling dynamic friction performance.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A friction test device simulating the sliding and rolling motion of a transmission mechanism, characterized in that: The overall structure includes a three-dimensional mechanical sensor, a torque sensor, a fastening screw group, an upper friction pair sleeve, an upper friction pair fixture, an upper friction pair plate, a raceway disc, a rolling element, a raceway disc support, and a rotating round table module; The three-dimensional mechanical sensor and torque sensor are connected to the host computer through the data acquisition card to measure the vertical pressure and friction torque between the upper friction plate and the rolling element in real time during the sliding and rolling friction test. The equivalent radius is calculated through the Hertz contact theory, and the friction coefficient is calculated and saved in real time in the host computer. The rotating table module is connected to the host computer through the programmable control board. The motor speed is adjusted to achieve the speed control of the rotating motion. The roller disc support is bolted to the rotating table module with 6 M2 screws. The pre-tightening force of each screw is ensured to be consistent. The torque wrench is used to tighten and the level is used to calibrate. The roller disc is bolted to the corresponding position of the roller disc support with four M3 screws. The polished upper friction pair plate and the upper friction pair fixture are bolted together using six M3 screws, and then the upper friction pair sleeve is tightened using an M4 screw to prevent the upper friction pair fixture from rotating and deviating during the sliding and rolling test; the assembled upper friction pair sleeve is installed at the corresponding position at the bottom of the torque sensor, and then the torque sensor is installed at the corresponding position of the three-dimensional mechanical sensor.

2. The friction test device for simulating the sliding and rolling motion of a transmission mechanism according to claim 1, characterized in that: The equivalent friction radius r0 is calculated as follows: Among them, r2 and r1 are the outer diameter and inner diameter of the actual friction contact area respectively, μ is the friction coefficient, r is the radius of the differential arc relative to the rotation center, σ is the contact stress at the infinitesimal point, Fz is the vertical pressure measured by the three-dimensional mechanical sensor, and r0 is the equivalent radius input to the host computer for calculating the friction coefficient between the upper friction pair plate and the rolling element; the equivalent radius between the rolling element and the raceway of the raceway is also calculated. The friction coefficient between the rolling element and the raceway of the raceway can be calculated through the ratio of the equivalent radii of the upper and lower friction contact areas of the rolling element and the measured friction coefficient between the upper friction pair plate and the rolling element.

3. A friction test method for simulating the sliding and rolling motion of a transmission mechanism, based on the test device according to claim 1, characterized in that: The test method includes the following general steps: Step 1: Install the three-dimensional mechanical sensor, torque sensor, and rotating table module in the test device at the corresponding position of the friction and wear testing machine, connect them to the host computer through the data acquisition card and program control board, and turn on the power to start and stop; Step 2: Use the host computer to control the center position of the torque sensor and align it with the center of the rotating table module and set it as the coordinate zero point; Step 3: Install the raceway disc on the raceway disc support by using M3 screws, and install the raceway disc support on the rotary table module by using M2 screws to complete the assembly of the bottom friction pair and the rotary drive module; Step 4: Connect the upper friction pair plate to the upper friction pair fixture with M3 screws, install the upper friction pair fixture on the upper friction pair sleeve with M4 screws, and then install the upper friction pair sleeve at the corresponding position at the bottom of the torque sensor to complete the assembly of the upper friction pair and the mechanical signal measurement module; Step 5: Apply a proper amount of grease to the raceway of the raceway disc and install the rolling element. Use the host computer to control the position of the torque sensor and the three-dimensional mechanical sensor so that the upper friction plate contacts the rolling element. Control the rotating frustum module to rotate, apply the grease evenly to the friction contact area, and complete the test run of the hot engine. Step 6: Set the speed, load, equivalent radius r0, and friction test duration of the sliding-rolling friction test through the host computer, and start the sliding-rolling friction test; Step 7: The collected mechanical signals are collected and processed by the host computer, and the real-time friction coefficient between the rolling element and the upper friction pair plate is output after calculation and processing; Step 8: Obtain the friction coefficient between the rolling element and the raceway of the raceway by calculating the equivalent radius between the rolling element and the raceway of the raceway.

Images